User:Mary Ball/AFP

WINTER FLOUNDER ANTIFREEZE PROTEIN
Type I antifreeze proteins (AFPs) are grouped together according to similar structure. The one shown on the right is from the winter flounder. This AFP consists of a chain of 37 amino acids: DTASDAAAAAALTAANAKAAAELTAANAAAAAAATAR The chain forms a single alpha-helix.

The four threonines are evenly spaced in the chain, such that there are three 11-amino-acid sequences. In the single alpha-helix that forms, the threonines all lie on one "face" of the helix.

See the location of the Threonine Residues.

See the Threonine Residues.

See one chain emphasized. Go back to the WFB Alpha Helix.

Baardsnes, et al (1999) created mutations that reduced the protein's ice-binding ability. They also compared the sequences of five different type I AFP molecules. They concluded that the "face" with the repeated Threonines promotes binding to ice crystals.

REFERENCE
New ice-binding face for type I antifreeze protein., Baardsnes J, Kondejewski LH, Hodges RS, Chao H, Kay C, Davies PL, FEBS Lett. 1999 Dec 10;463(1-2):87-91. PMID:10601644

ABOUT THIS STRUCTURE
1WFB is a 2 chains structure with sequences from Pseudopleuronectes americanus. The December 2009 RCSB PDB Molecule of the Month feature on Antifreeze Proteins by David Goodsell is 10.2210/rcsb_pdb/mom_2009_12. Full crystallographic information is available from OCA.

REFERENCE
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